Study of enzymatic properties of phenol oxidase from nitrogen-fixing Azotobacter chroococcum

Herter, Susanne; Schmidt, Marlen; Thompson, Mark L; Mikolasch, Annett; Schauer, Frieder

doi:10.1186/2191-0855-1-14

AMB Express

Table 2 Examination of substrate preferences towards model compounds exhibited by PO containing cell-free extract from A. chroococcum SBUG 1484 compared to fungal crude PO preparations from P. cinnabarinus SBUG-M 1044 and PPO from A. bisporus

From: Study of enzymatic properties of phenol oxidase from nitrogen-fixing Azotobacter chroococcum

	Initial rate of activity (ΔA min^-1 mL^-1 × factor 1,000)
Model compound	Wavelength [nm]	*A. chroococcum* PO	*P. cinnabarinus* PO	*A. bisporus* PPO
Compound group 1
Guaiacol	436	10	28	2
para-Vanillin	436	0^a	0	0
ortho-Vanillin	468	40	28	0
Vanillin acid	436	0	0	0
Vanillin alcohol	420	42	0	0
Vanillin azine	468	0	6	0
4-Hydroxy-3-methoxy-α- methylbenzyl alcohol	420	24	0	0
2-Methoxy-6-methylphenol	468	54	0	0
2-Methoxy-4-methylphenol	420	34	0	0
2-Methoxy-4-propylphenol	420	84	0	0
2-Hydroxy-6-methoxybenzaldehyde	420	0	0	0
2-Hydroxy-5-methoxybenzaldehyde	420	36	4	0
Eugenol	420	76	32	0
Ferulic acid	480	0	0	0
Compound group 2
2,6-Dimethoxyphenol (2,6-DMP)	468	746	532	20
2,3-Dimethoxyphenol	468	5	0.6	0.2
Syringic acid	468	0.8	0.4	0.4
Syringaldehyde	468	1	0.4	0.2
4-Methyl-2,6-dimethoxyphenol	468	0.6	0.2	0
2,6-Dimethylphenol	468	0.7	1.8	0.6
Syringaldazine	525	0	22.4	0
Compound group 3
Catechol	450	9	2.5	934
3-Methylcatechol	420	29	30	412
4-Methylcatechol	420	24	8	572
tert-Butylcatechol	420	13	8	886
3-Methoxycatechol	420	13	9	52
3-Isopropylcatechol	420	34	20	362
Hydrocaffeic acid	530	1.5	0	74
Compound group 4
Hydroquinone	285	0.5	1	0
2-Methylhydroquinone	285	0.5	1.2	0.2
2-Methoxyhydroquinone	285	0.8	2.4	1.2
tert-Butylhydroquinone	285	0.4	1.6	0.8
2,3-Dimethylhydroquinone	400	0.8	0.6	0
2,6-Dimethoxyhydroquinone	400	2.6	3	0
Compound group 5
4-Hydroxyindole	400	5	6	4
3-(3,4-Dihydroxyphenyl)-L-alanine	475	4	3	388
Tyrosine^b	280	0	0	6
Dopamine	400	8	2.3	448
3,4-Dihydroxybenzoic acid	400	0.6	2	8
3,4-Dihydroxyphenylacetic acid	400	1	3	1,072
Compound group 7
ABTS	420	582	638	18
Pyrogallole	450	108	14	170
para-Phenylenediamine	523	78	90	30
para-Cresol	300	0	0	8

Initial rate of enzyme activity was measured with values shown multiplied by a factor of 1,000.
^a Change in absorbance could not be determined within prolonged incubation times, highlighting the compound as a non-enzyme substrate under the conditions applied.
^b Assaying the oxidation of tyrosine (compound group 5) and p-cresol (compound group 7) was accomplished after a pre-incubation period of 5 minutes at 25°C.

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